- Bec's principal research interests are in the area of climate change impacts on biodiversity, species distributions a... moreBec's principal research interests are in the area of climate change impacts on biodiversity, species distributions and thermal biology. Her current role as Climate Research Fellow involves working with regional climate projections to contribute to landscape management decisions that are necessary to adapt to climate change impacts.
She has almost 20 years’ experience working in research organisations, including the Australian Museum (Arachnology Section and the Centre for Biodiversity and Conservation Research), the Key Centre for Biodiversity and Bioresources, Macquarie University, and the University of Tasmania (School of Geography and the Antarctic Ecosystem and Climate CRC). She has worked in the areas of invertebrate and botanical biodiversity assessment, island biogeography and disturbance ecology, and more recently applied this experience to studying climate change impacts on natural and agricultural ecosystems.edit
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Fire is a complex process involving interactions and feedbacks between biological, socioeconomic, and physical drivers across multiple spatial and temporal scales. This complexity limits our ability to incorporate fire into Earth system... more
Fire is a complex process involving interactions and feedbacks between biological, socioeconomic, and physical drivers across multiple spatial and temporal scales. This complexity limits our ability to incorporate fire into Earth system models and project future fire activity under climate change. Conceptual, empirical, and process models have identified the mechanisms and processes driving fire regimes, and provide a useful basis to consider future fire activity. However, these models generally deal with only one component of fireregimes, fire frequency and do not incorporate feedbacks between fire, vegetation, and climate. They are thus unable to predict the location, severity or timing of fires, the socioecological impacts of fireregimechange, or potential non-linear responses such as biome shifts into alternative stable states. Dynamic modeling experiments may facilitate more thorough investigations of fire– vegetation–climate feedbacks and interactions, but their success will depend on the development of dynamic global vegetation models (DGVMs) that more accurately represent biological drivers. This requires improvements in the representation of current vegetation, plant responses to fire, ecological dynamics, and land management to capture the mechanisms behind fire frequency, intensity, and timing. DGVMs with fire modules are promising tools to develop a globally consistent analysis of fire activity, but projecting future fire activity will ultimately require a transdisciplinary synthesis of the biological, atmospheric, and socioeconomic drivers of fire. This is an important goal because fire causes substantial economic disruption and contributes to future climate change through its influence on albedo and the capacity of the biosphere to store carbon.
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A framework for identifying species that may become invasive under future climate conditions is presented, based on invader attributes and biogeography in combination with projections of future climate. We illustrate the framework using... more
A framework for identifying species that may become invasive under future climate conditions is presented, based on invader attributes and biogeography in combination with projections of future climate. We illustrate the framework using the CLIMEX niche model to identify future climate suitability for three species of Hawkweed that are currently present in the Australian Alps region and related species that are present in the neighbouring region. Potential source regions under future climate conditions are identified, and species from those emergingriskareasareidentified.Weusedynamically downscaled climate projections to complement global analyses and provide fine-scale projections of suitable climate for current and future (2070–2099) conditions at the regional scale. Changing climatic conditions may reduce the suitability for some invasive species and improve it for others. Invasive species with distributions strongly determined by climate, where the projected future climate is highly suitable, are those with the greatest potential to be future invasive species in the region. As the Alps region becomes warmer and drier, many more regions of the world become potential sources of invasive species, although only one additional species of Hawkweed is identified as an emerging risk. However, in the longer term, as the species in these areas respond to global climate change, the potential source areas contract again to match higher altitude regions. Knowledge of future climate suitability, based on species-specific climatic tolerances, is a useful step towards prioritising management responses such as targeted eradication and early intervention to prevent the spread of future invasive species.
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Effective conservation of threatened ecological communities requires knowledge of where climatically suitable habitat is likely to persist into the future. We use the critically endangered Lowland Grassland community of Tasmania,... more
Effective conservation of threatened ecological communities requires knowledge of where climatically suitable habitat is likely to persist into the future. We use the critically endangered Lowland Grassland community of Tasmania, Australia as a case study to identify options for management in cases where future climatic conditions become unsuitable for the current threatened community.
We model current and future climatic suitability for the Lowland Themeda and the Lowland Poa Grassland communities, which make up the listed community. We also model climatic suitability for the structurally dominant grass species of these communities, and for closely related grassland and woodland communities. We use a dynamically downscaled regional climate model derived from six CMIP3 global climate models, under the A2 SRES emissions scenario. All model projections showed a large reduction in climatically suitable area by mid-century. Outcomes are slightly better if closely related grassy communities are considered, but the extent of suitable area is still substantially reduced. Only small areas within the current distribution are projected to remain climatically suitable by the end of the century, and very little of that area is currently in good condition.
As the climate becomes less suitable, a gradual change in the species composition, structure and habitat quality of the grassland communities is likely. Conservation management will need to be responsive and dynamic, and focus on maintaining diversity, structure and function, rather than attempting to preserve current species composition. Options for achieving this include managing related grassland types to maintain grassland species at the landscape-scale, and maximising the resilience of grasslands by reducing further fragmentation, weed invasion and stress from other land uses, while accepting that change is inevitable. Attempting to maintain the status quo by conserving the current structure and composition of Lowland Grassland communities is unlikely to be a viable management option in the long term.
We model current and future climatic suitability for the Lowland Themeda and the Lowland Poa Grassland communities, which make up the listed community. We also model climatic suitability for the structurally dominant grass species of these communities, and for closely related grassland and woodland communities. We use a dynamically downscaled regional climate model derived from six CMIP3 global climate models, under the A2 SRES emissions scenario. All model projections showed a large reduction in climatically suitable area by mid-century. Outcomes are slightly better if closely related grassy communities are considered, but the extent of suitable area is still substantially reduced. Only small areas within the current distribution are projected to remain climatically suitable by the end of the century, and very little of that area is currently in good condition.
As the climate becomes less suitable, a gradual change in the species composition, structure and habitat quality of the grassland communities is likely. Conservation management will need to be responsive and dynamic, and focus on maintaining diversity, structure and function, rather than attempting to preserve current species composition. Options for achieving this include managing related grassland types to maintain grassland species at the landscape-scale, and maximising the resilience of grasslands by reducing further fragmentation, weed invasion and stress from other land uses, while accepting that change is inevitable. Attempting to maintain the status quo by conserving the current structure and composition of Lowland Grassland communities is unlikely to be a viable management option in the long term.
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Climate projections are essential for studying ecological responses to climate change, and their use is now common in ecology. However, the lack of integration between ecology and climate science has restricted understanding of the... more
Climate projections are essential for studying ecological responses to climate change, and their use is now common in ecology. However, the lack of integration between ecology and climate science has restricted understanding of the available climate data and their appropriate use. We provide an overview of climate model outputs and issues that need to be considered when applying projections of future climate in ecological studies. We outline the strengths and weaknesses of available climate projections, the uncertainty associated with future projections at different spatial and temporal scales, the differences between available downscaling methods (dynamical, statistical downscaling and simple scaling of Global Circulation Model output), and the implications these have for ecological models. We describe some of the changes in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), including the new Representative Concentration Pathways. We highlight some of the challenges in using model projections in ecological studies and suggest how to effectively address them.
Projected changes to the global climate system have great implications for the incidence of large infrequent fires in many regions. Here we examine the synoptic-scale and local-scale influences on the incidence of extreme fire weather... more
Projected changes to the global climate system have great implications for the incidence of large infrequent fires in many regions. Here we examine the synoptic-scale and local-scale influences on the incidence of extreme fire weather days and consider projections of the large-scale mean climate to explore future fire weather projections. We focus on a case study region with periodic extreme fire dangers; southeast Tasmania, Australia. We compare the performance of a dynamically downscaled regional climate model with Global Climate Model outputs as a tool for examining the local-scale influences while accounting for high
regional variability. Many of the worst fires in Tasmania and the southeast Australian region are associated with deep cold fronts and strong prefrontal winds. The downscaled simulations reproduce this synoptic type with greater fidelity than a typical global climate model. The incidence of systems in this category is projected to increase through the century under a high emission scenario, driven mainly by an increase in the temperature of air masses, with little change in the strength of the systems. The regional climate model projected increase in frequency is smaller than for the global climate models used as input, with a large model range and natural variability. We also demonstrate how a blocking Foehn effect and topographic channelling contributed to the extreme conditions during an extreme fire weather day in Tasmania in January 2013. Effects such as these are likely to contribute to high fire danger throughout the century. Regional climate models are useful tools that enable various meteorological drivers of fire danger to be considered in projections of future fire danger.
regional variability. Many of the worst fires in Tasmania and the southeast Australian region are associated with deep cold fronts and strong prefrontal winds. The downscaled simulations reproduce this synoptic type with greater fidelity than a typical global climate model. The incidence of systems in this category is projected to increase through the century under a high emission scenario, driven mainly by an increase in the temperature of air masses, with little change in the strength of the systems. The regional climate model projected increase in frequency is smaller than for the global climate models used as input, with a large model range and natural variability. We also demonstrate how a blocking Foehn effect and topographic channelling contributed to the extreme conditions during an extreme fire weather day in Tasmania in January 2013. Effects such as these are likely to contribute to high fire danger throughout the century. Regional climate models are useful tools that enable various meteorological drivers of fire danger to be considered in projections of future fire danger.
Species distribution models (SDMs) are commonly used to project future changes in the geographic ranges of species, estimate extinction rates and plan biodiversity conservation. However, these models can produce a range of results... more
Species distribution models (SDMs) are commonly used to project future changes in the geographic ranges of species, estimate extinction rates and plan biodiversity conservation. However, these models can produce a range of results depending on how they are parameterized, and over-reliance on a single model may lead to over-confidence in maps of future distributions.
The choice of predictor variable can have a greater influence on projected future habitat than the range of climate models used. We demonstrate this in the case of the Ptunarra Brown Butterfly, a species listed as vulnerable in Tasmania, Australia. We use the Maxent model to develop future projections for this species based on three variable sets; all 35 commonly used so-called “bioclimatic” variables, a subset of these based on expert knowledge, and a set of monthly climate variables relevant to the species’ primary activity period. We used a dynamically downscaled regional climate model based on three global climate models. Depending on the choice of variable set, the species is projected either to experience very little contraction of habitat or to come close to extinction by the end of the century due to lack of suitable climate. The different conclusions could have important consequences for conservation planning and management, including the perceived viability of habitat restoration. The output of SDMs should therefore be used to define the range of possible trajectories a species may be on, and ongoing monitoring used to inform management as changes occur.
The choice of predictor variable can have a greater influence on projected future habitat than the range of climate models used. We demonstrate this in the case of the Ptunarra Brown Butterfly, a species listed as vulnerable in Tasmania, Australia. We use the Maxent model to develop future projections for this species based on three variable sets; all 35 commonly used so-called “bioclimatic” variables, a subset of these based on expert knowledge, and a set of monthly climate variables relevant to the species’ primary activity period. We used a dynamically downscaled regional climate model based on three global climate models. Depending on the choice of variable set, the species is projected either to experience very little contraction of habitat or to come close to extinction by the end of the century due to lack of suitable climate. The different conclusions could have important consequences for conservation planning and management, including the perceived viability of habitat restoration. The output of SDMs should therefore be used to define the range of possible trajectories a species may be on, and ongoing monitoring used to inform management as changes occur.
Altitudinal clines in melanism are generally assumed to reflect the fitness benefits resulting from thermal differences between colour morphs, yet differences in thermal quality are not always dis-cernible. The intra-specific application... more
Altitudinal clines in melanism are generally assumed to reflect the fitness benefits resulting from thermal differences between colour morphs, yet differences in thermal quality are not always dis-cernible. The intra-specific application of the thermal melanism hypothesis was tested in the wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae) first by measur-ing the thermal properties of the different colour morphs in the laboratory, and second by testing for differences in average reflectance and spectral characteristics of populations along 14 altitu-dinal gradients. Correlations between reflectance, body size, and climatic variables were also tested to investigate the underlying causes of clines in melanism. Melanism in P. vittatum repre-sents a gradation in colour rather than distinct colour morphs, with reflectance ranging from 2.49 to 5.65%. In unstriped grasshoppers, darker morphs warmed more rapidly than lighter morphs and reached a higher maximum temperature (lower temperature excess). In contrast, significant differences in thermal quality were not found between the colour morphs of striped grasshoppers. In support of the thermal melanism hypothesis, grasshoppers were, on average, darker at higher altitudes, there were differences in the spectral properties of brightness and chroma between high and low altitudes, and temperature variables were significant influences on the average reflec-tance of female grasshoppers. However, altitudinal gradients do not represent predictable variation in temperature, and the relationship between melanism and altitude was not consistent across all gradients. Grasshoppers generally became darker at altitudes above 800 m a.s.l., but on several gradients reflectance declined with altitude and then increased at the highest altitude.
"ABSTRACT Aim We explore geographic variation in body size within the wingless grasshopper, Phaulacridium vittatum, along a latitudinal gradient, and ask whether melanism can help explain the existence of clinal variation. We test the... more
"ABSTRACT
Aim We explore geographic variation in body size within the wingless grasshopper, Phaulacridium vittatum, along a latitudinal gradient, and ask whether melanism can help explain the existence of clinal variation. We test the hypotheses that both male and female grasshoppers will be larger and lighter in colour at lower latitudes, and that reflectance and size will be positively correlated, as predicted by biophysical theory. We then test the hypothesis that variability in size and reflectance is thermally driven, by assessing correlations with temperature and other climatic variables.
Location Sixty-one populations were sampled along the east coast of Australia between latitudes 27.63 S and 43.10 S, at elevations ranging from 10 to 2000 m a.s.l.
Methods Average reflectance was used as a measure of melanism and femur length as an index of body size for 198 adult grasshoppers. Climate variables were generated by BIOCLIM for each collection locality. Hierarchical partitioning was
used to identify those variables with the most independent influence on grasshopper size and reflectance.
Results Overall, there was no simple relationship between size and latitude in P. vittatum. Female body size decreased significantly with latitude, while male body size was largest at intermediate latitudes. Rainfall was the most important
climatic variable associated with body size of both males and females. Female body size was also associated with radiation seasonality and male body size with reflectance. The reflectance of females was not correlated with latitude or body size, while male reflectance was significantly higher at intermediate latitudes and positively correlated with body size. Analyses of climate variables showed no significant association with male reflectance, while female reflectance was significantly related to the mean temperature of the driest quarter.
Main conclusions Geographic variation in the body size of the wingless grasshopper is best explained in terms of rainfall and radiation seasonality, rather than temperature. However, melanism is also a significant influence on body size in male grasshoppers, suggesting that thermal fitness does play a role in
determining adaptive responses to local conditions in this sex."
Aim We explore geographic variation in body size within the wingless grasshopper, Phaulacridium vittatum, along a latitudinal gradient, and ask whether melanism can help explain the existence of clinal variation. We test the hypotheses that both male and female grasshoppers will be larger and lighter in colour at lower latitudes, and that reflectance and size will be positively correlated, as predicted by biophysical theory. We then test the hypothesis that variability in size and reflectance is thermally driven, by assessing correlations with temperature and other climatic variables.
Location Sixty-one populations were sampled along the east coast of Australia between latitudes 27.63 S and 43.10 S, at elevations ranging from 10 to 2000 m a.s.l.
Methods Average reflectance was used as a measure of melanism and femur length as an index of body size for 198 adult grasshoppers. Climate variables were generated by BIOCLIM for each collection locality. Hierarchical partitioning was
used to identify those variables with the most independent influence on grasshopper size and reflectance.
Results Overall, there was no simple relationship between size and latitude in P. vittatum. Female body size decreased significantly with latitude, while male body size was largest at intermediate latitudes. Rainfall was the most important
climatic variable associated with body size of both males and females. Female body size was also associated with radiation seasonality and male body size with reflectance. The reflectance of females was not correlated with latitude or body size, while male reflectance was significantly higher at intermediate latitudes and positively correlated with body size. Analyses of climate variables showed no significant association with male reflectance, while female reflectance was significantly related to the mean temperature of the driest quarter.
Main conclusions Geographic variation in the body size of the wingless grasshopper is best explained in terms of rainfall and radiation seasonality, rather than temperature. However, melanism is also a significant influence on body size in male grasshoppers, suggesting that thermal fitness does play a role in
determining adaptive responses to local conditions in this sex."
Research Interests:
Background/Question/Methods The long-term viability of highly fragmented threatened communities depends on the climate remaining suitable into the future. Changing climatic suitability may lead to shifts in the distribution of some or... more
Background/Question/Methods
The long-term viability of highly fragmented threatened communities depends on the climate remaining suitable into the future. Changing climatic suitability may lead to shifts in the distribution of some or all species, resulting in an altered community with a different composition, structure and, possibly, function.
We identify possible options for managing threatened communities under climate change, using the Lowland Grassland community (LNGT) in Tasmania, Australia, as a case study. We test whether future climate conditions are likely to remain suitable for the lowland grassland community. We do this by modelling the current and future climatic suitability for the community as a whole, for the structurally dominant species, and for the areas that are currently in the best condition. We use a correlative species distribution model (Maxent) and climate projections from six dynamically downscaled climate models to project the change in climatic suitability for this community from the present to the end of the century.
Results/Conclusions
The current distribution of the LNGT is already highly restricted, and the projections suggest it will contract substantially over the next century due to climate change. The projected contraction is so substantial that it is unlikely that the grassland community will continue in its current form.
However, when the dominant species, Poa labillardierei and Themeda triandra, are modelled separately, climatically suitable areas are projected to persist within the current distribution. This provides options for managing the community, but only if the dynamic nature of changing communities under climate change is acknowledged. Current planning and policy frameworks are unable to do so, since they aim to maintain the current composition and structure. Areas of the best condition are likely to be the most resilient to change and the most likely to maintain function under changing climatic conditions. These areas should be the focus of conservation efforts.
The long-term viability of highly fragmented threatened communities depends on the climate remaining suitable into the future. Changing climatic suitability may lead to shifts in the distribution of some or all species, resulting in an altered community with a different composition, structure and, possibly, function.
We identify possible options for managing threatened communities under climate change, using the Lowland Grassland community (LNGT) in Tasmania, Australia, as a case study. We test whether future climate conditions are likely to remain suitable for the lowland grassland community. We do this by modelling the current and future climatic suitability for the community as a whole, for the structurally dominant species, and for the areas that are currently in the best condition. We use a correlative species distribution model (Maxent) and climate projections from six dynamically downscaled climate models to project the change in climatic suitability for this community from the present to the end of the century.
Results/Conclusions
The current distribution of the LNGT is already highly restricted, and the projections suggest it will contract substantially over the next century due to climate change. The projected contraction is so substantial that it is unlikely that the grassland community will continue in its current form.
However, when the dominant species, Poa labillardierei and Themeda triandra, are modelled separately, climatically suitable areas are projected to persist within the current distribution. This provides options for managing the community, but only if the dynamic nature of changing communities under climate change is acknowledged. Current planning and policy frameworks are unable to do so, since they aim to maintain the current composition and structure. Areas of the best condition are likely to be the most resilient to change and the most likely to maintain function under changing climatic conditions. These areas should be the focus of conservation efforts.
Changing phenology has been identified as one of the most important impacts of climate change on biodiversity. Periodic life cycle events such as emergence, breeding and migration are important determinants of species distributions,... more
Changing phenology has been identified as one of the most important impacts of climate change on biodiversity. Periodic life cycle events such as emergence, breeding and migration are important determinants of species distributions, species interactions and the structure and function of all ecosystems.
Growing degree days (GDD) are a measure of heat accumulation that can be used to link phenology to the underlying climate drivers that are projected to change over the next century. Using daily maximum and minimum temperatures from a regional climate model for Tasmania, Australia, we demonstrate the changes that are projected to occur in the total GDD for the growing season, the start and end dates of the growing season and the time taken to accumulate GDD. We present results from 6 downscaled global climate models (GCMs) and three future periods, 2020, 2050 and 2080. We also show the shifts in the growing season that have occurred in Tasmania since 1901. We calculate GDD for various base and upper temperatures to account for the different thermal requirements of a range of insects and their host plants, including pest species (European wasp, Codling Moth) and endemic insects of high conservation significance (Ptunarra Brown Butterfly). Different methods of calculating GDD give slightly different results, but the overall trend is for earlier and longer growing seasons. We relate these projected changes to the GDD requirements for development, to illustrate the potential for shifts in phenology under climate change.
Growing degree days (GDD) are a measure of heat accumulation that can be used to link phenology to the underlying climate drivers that are projected to change over the next century. Using daily maximum and minimum temperatures from a regional climate model for Tasmania, Australia, we demonstrate the changes that are projected to occur in the total GDD for the growing season, the start and end dates of the growing season and the time taken to accumulate GDD. We present results from 6 downscaled global climate models (GCMs) and three future periods, 2020, 2050 and 2080. We also show the shifts in the growing season that have occurred in Tasmania since 1901. We calculate GDD for various base and upper temperatures to account for the different thermal requirements of a range of insects and their host plants, including pest species (European wasp, Codling Moth) and endemic insects of high conservation significance (Ptunarra Brown Butterfly). Different methods of calculating GDD give slightly different results, but the overall trend is for earlier and longer growing seasons. We relate these projected changes to the GDD requirements for development, to illustrate the potential for shifts in phenology under climate change.